Since the invention of concrete with imbedded metal by Monier in 1849, load bearing structures have been built using a material with high compressive strength, embedded with a filament, wire or cable (collectively called the tensile members). In this fashion, most modern structures (bridges, columns, etc.) are built with a very large mass of concrete (mostly cement plus an aggregate), placed in tension via its own weight and the addition of said tensile members. Said large masses are required, for the tensile member would usually be worthless in the compressive mode.
Their structural mass (for in effect a bridge is many times heavier than its traffic payload) becomes at times a burden. As recent events in Haiti, Chile and China so aptly demonstrate, these same large masses have a sad and detrimental effect on the human population when natural phenomena such as earthquakes occur. Besides the amount of human lives that are loss during and shortly after the event, the significant amount of detritus created by these events causes the habitat around the disaster zone to be affected for years by the cost of its removal.
As seen in U.S. Pat. Nos. 3,854,253, 4,004,380, 4,676,032, 5,675,938 and 6,584,732, inflatable structures that have interior braces, cables, and films to maintain the geometry of the structure have been taught. These are not however, designed to be used in the construction of building blocks for larger structures, being in effect “fluffy” balloons. Between the connecting points of the cables to the outer surfaces, the outer surface material typically bulges out, due to the air pressure. If these were used as building blocks, when one block is placed upon another, the bulges would be springy and would compress so that there would not be sufficient rigidity for effective building blocks.
The above also includes use of the building blocks for the construction of convection towers, seen in U.S. Pat. Nos. 5,284,628; 5,395,598; 5,477,684; and 5,483,798; as well as US Pat. Appl. No. 20090260301 (all by Prueitt). They have in common the use of air compression blocks utilizing external tensile members to provide the tensile means. Drake (U.S. Pat. No. 6,484,469) utilizes moving pistons to perform some loading, but of course movement would require significant dynamic seal technology.
What is needed is a structure using a fluid (be it a gas, liquid or combination thereof) as the compression member, and either internal or external tensile means to help in keeping the compressed gas, liquid or combination thereof within an envelope or cavity, so that a relatively lightweight structural member may be produced for use in the construction of composite structural elements.